Re: kexec on rk3399

[Robin Murphy]

On 14/08/2019 13:53, Vicente Bergas wrote:
> On Monday, July 22, 2019 4:31:27 PM CEST, Vicente Bergas wrote:
> > Hi, i have been running linux on rk3399 booted with kexec fine until 5.2
> > From 5.2 onwards, there are memory corruption issues as reported here:
> > http://lkml.iu.edu/hypermail/linux/kernel/1906.2/07211.html
> > kexec has been identified as the principal reason for the issues.
> >
> > It turns out that kexec has never worked reliably on this platform,
> > i was just lucky until recently.
> >
> > Please, can you provide some directions on how to debug the issue?
>
> Thank you all for your suggestions on where the issue could be.
>
> It seems that it was the USB driver.
> Now using v5.2.8 booted with kexec from v5.2.8 with a workaround and
> so far so good. It is being tested on the Sapphire board.
>
> The workaround is:
> --- a/drivers/usb/dwc3/dwc3-of-simple.c
> +++ b/drivers/usb/dwc3/dwc3-of-simple.c
> @@ -133,6 +133,13 @@
>  ÂÂÂÂreturn 0;
> }
>
> +static void dwc3_of_simple_shutdown(struct platform_device *pdev)
> +{
> +ÂÂÂ struct dwc3_of_simple *simple = platform_get_drvdata(pdev);
> +
> +ÂÂÂ reset_control_assert(simple->resets);
> +}
> +
> static int __maybe_unused dwc3_of_simple_runtime_suspend(struct device 
> *dev)
> {
>  ÂÂÂÂstruct dwc3_of_simpleÂÂÂ *simple = dev_get_drvdata(dev);
> @@ -190,6 +197,7 @@
> static struct platform_driver dwc3_of_simple_driver = {
>  ÂÂÂÂ.probeÂÂÂÂÂÂÂ = dwc3_of_simple_probe,
>  ÂÂÂÂ.removeÂÂÂÂÂÂÂ = dwc3_of_simple_remove,
> +ÂÂÂ .shutdownÂÂÂ = dwc3_of_simple_shutdown,
>  ÂÂÂÂ.driverÂÂÂÂÂÂÂ = {
>  ÂÂÂÂÂÂÂ .nameÂÂÂ = "dwc3-of-simple",
>  ÂÂÂÂÂÂÂ .of_match_table = of_dwc3_simple_match,
>
> If this patch is OK after review i can resubmit it as a pull request.
> Should a similar change be applied to drivers/usb/dwc3/core.c ?

This particular change looks like it's implicitly specific to RK3399, 
which wouldn't be ideal. Presumably if the core dwc3 driver implemented 
shutdown correctly (echoing parts of dwc3_remove(), I guess) then the 
glue layers shouldn't need anything special anyway.

Robin.